1. Field of the Invention
The present invention relates to an image forming device, more particularly, to an apparatus to feed paper in an image forming device, which picks up papers of various thicknesses in a feeding stand of the image forming device, and transfers the same to a developing unit without a feeding error.
2. Description of the Related Art
FIG. 1 is a perspective view of a conventional apparatus to feed paper in a printing apparatus that comprises: a feeding cassette 10 in which paper is received, and a pickup unit 20 to pick up the received paper.
The feeding cassette 10 receives a plurality of papers to allow the printing apparatus to sequentially perform print operations. The feeding cassette 10 has a dam-type separating guide 11 with which a front end of the paper makes contact, and the separating guide 11 is provided with at least one friction plate 12.
The pickup unit 20 is installed to the main machine of the printing apparatus (not shown) corresponding to the feeding cassette 10 provided. The pickup unit 20 includes: a pickup roller 21 to pick up the paper in the feeding cassette 10; a pickup arm 22 having a gear train to operate the pickup roller; and an operating motor 23 to deliver power to the pickup arm 22.
According to the conventional feeding apparatus, when the operating motor 23 operates according to a print signal from a controlling unit (not shown), the pickup roller 21 rotates via the gear train, and the paper is picked up by rotation of the pickup roller 21. The picked up paper P is separated and transferred by the separating guide 11 installed to a front end of the feeding cassette 10.
According to the conventional apparatus, a predetermined distance between the pickup roller 21 and the separating guide 11 is maintained regardless of the thickness of the paper, thus, overlapped transfer of papers could occur when paper with low stiffness (e.g. a thin paper) is picked up, and a printing error is generated due to a pick up error when paper with high stiffness (e.g. a thick paper) is picked up.
In addition, because the distance between the pickup roller 21 and the separating guide 11 is maintained constant, and a slope of the separating guide 11 is fixed, a high torque is required to pick up a thick paper, resulting in high power consumption and damage to the front end of the paper due to a resisting force against the separating guide 11.